Here's a closer photo from the same page.
There's a center rail which is connected to both of the 3 spoke hull connections which stays on the center line.
It also holds the mast and forestay.
The jib is self tending and the boomless main is sheeted to the aft end of the center rail.
The mast has conventional stays which go to the mats which are apparently fixed to the center rail.
The boat from the base of the mast including the mats is strictly a standard self tending jib type boat.
It's only the hulls which swivel below that is novel (and bizarre).
I'm still trying to figure out where the rudder attaches.

Looks like a tacking version of a proa, where they reconfigure the main hull on each tack rather than shuttle like you would on a traditional proa.

Exactly. I like your use of the word shuttle. It conveys better what happens during a shunt. This construction also demonstrates in absurdum how effectively simple proa's are for the very same sailing advantages.

Exactly. I like your use of the word shuttle. It conveys better what happens during a shunt. This construction also demonstrates in absurdum how effectively simple proa's are for the very same sailing advantages.

Actually I meant shunt but that's neither here nor there.

For a small dingy type application I really like the proa idea for it's simplicity. This thing does not look simple by any stretch of the imagination.

Some day I have to finish the 14' proa that is sitting in my brother-in-laws pole barn. It's largely built but needs finish work. The problem is we headed out cruising.
- All but the main hull can be quickly dissassembled and stored in the extra cabin or the whole thing can hang from the davits (estimated weight 60-80lbs).
- With the narrow hulls, it should padle as easily as a canoe.
- A little 2hp outboard on the cross arm should move it along nicely
- A simple lateen sail is planned with a mounting point on the cross arms to use a paddle as a rudder.
- High freeboard compared to an inflatable should make it dry.
- With a ladder mounded between the hulls, it should be easy and stable to climb in and out from the water.
- Solid hull so no holes like inflatables get.

For a small dingy type application I really like the proa idea for it's simplicity. This thing does not look simple by any stretch of the imagination.

Some day I have to finish the 14' proa that is sitting in my brother-in-laws pole barn. It's largely built but needs finish work. The problem is we headed out cruising.
- All but the main hull can be quickly dissassembled and stored in the extra cabin or the whole thing can hang from the davits (estimated weight 60-80lbs).
- With the narrow hulls, it should padle as easily as a canoe.
- A little 2hp outboard on the cross arm should move it along nicely
- A simple lateen sail is planned with a mounting point on the cross arms to use a paddle as a rudder.
- High freeboard compared to an inflatable should make it dry.
- With a ladder mounded between the hulls, it should be easy and stable to climb in and out from the water.
- Solid hull so no holes like inflatables get.

The builder of this boat has done the opposite: a catamaran "dingy" fitting its hulls alongside as fairings to the beams of this large HarryProa.